[SPARK-18816][WEB UI] Executors Logs column only ran visibility check on initial table load

## What changes were proposed in this pull request?

When I added a visibility check for the logs column on the executors page in #14382 the method I used only ran the check on the initial DataTable creation and not subsequent page loads. I moved the check out of the table definition and instead it runs on each page load. The jQuery DataTable functionality used is the same.

## How was this patch tested?

Tested Manually

No visible UI changes to screenshot.

Author: Alex Bozarth <ajbozart@us.ibm.com>

Closes #16256 from ajbozarth/spark18816.

core/src/main/resources/org/apache/spark/ui/static/executorspage.js

@@ -411,10 +411,6 @@ $(document).ready(function () {
                         }
                     ],
                     "columnDefs": [
-                        {
-                            "targets": [ 15 ],
-                            "visible": logsExist(response)
-                        },
                         {
                             "targets": [ 16 ],
                             "visible": getThreadDumpEnabled()
@@ -423,7 +419,8 @@ $(document).ready(function () {
                     "order": [[0, "asc"]]
                 };
     
-                $(selector).DataTable(conf);
+                var dt = $(selector).DataTable(conf);
+                dt.column(15).visible(logsExist(response));
                 $('#active-executors [data-toggle="tooltip"]').tooltip();
     
                 var sumSelector = "#summary-execs-table";